Freedom Group (Remington, DPMS/Panther, et al.) went bankrupt in March 2018, and all assets were sold off in Sept 2020. JJE Capitol, the parent company of Palmetto State Armory, purchased the rights to the DPMS/Panther brand, no physical property was listed as included. Before the sale, some of the existing DPMS stock was liquidated through a couple of vendors, the largest being CDNN, and most or all of the GII proprietary parts have since sold out. Some have stated that a significant amount of parts were loaded into bins and sold as scrap. GII proprietary parts are now considered rare. PSA has no plans at this time to revive or support the GII. Patent infringement pretty much excludes third party production of proprietary GII parts.
The GII is a great rifle, Mine has been trouble-free, however, I now treat it much more carefully than most my other rifles. There are still options for parts, none cheap.
The spring itself is common, The dust cover/rod/clip is proprietary. I don't believe that the dust cover assembly linked above is GII compatible. Here's a compatibility chart that might be helpful:
.